Transcript BioE Example: Artificial Heart

The Artificial Heart:
A Design Example
BIOE 1000
October 18, 2001
The Human Heart

Heart has four
chambers
 Right chambers
pump blood to lungs
to receive oxygen
 Left chambers pump
oxygenated blood
from lungs to rest of
the body
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The Human Heart
Right and left atria receive blood
 Right and left ventricles pump blood
 Valves produce one-way blood flow
from atria  ventricles  arteries
 Energy to pump blood comes from
nutrients and oxygen in blood
 The blood supply to the heart is
provided by coronary arteries
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Heart Disease

Heart attack: blockage of coronary artery
damages portion of heart muscle
 Congestive heart failure: gradual weakening
of heart
 Millions suffer from heart disease
– Many cases are treatable with lifestyle changes,
drugs and/or surgery
– Surviving patients suffering from most severe
cases need new hearts!
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The Need for a Heart
Substitute
100,000 Americans/year suffering from
severe heart disease need new hearts
 Only 2,000 patients receive heart
transplants
 Conclusion: many patients die waiting
for a new heart!
 A suitable alternative to donor hearts
could prolong thousands of lives

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History of Heart
Substitutes
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WWII: first open heart
surgeries
1953: heart-lung machine
successfully used during
heart surgery
1958: Drs. Willem Kolff and
Tetsuzo Akutsu sustain a
dog for 90 minutes with a
PVC artificial heart
1967: Dr. Christian Barnard
transplants a donor heart
into a 59 year old man (he
survived 18 days)
PVC heart (1958)
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silicone heart (1965)
History of Heart
Substitutes
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Liotta heart (1969)
Jarvik-7 (1982)
1969: Dr. Denton Cooley
uses an artificial heart to
sustain a patient waiting for
a donor (survived 3 days)
1972: Cyclosporine
introduced to suppress
immune responses of
transplant recipients
1982: Dr. William DeVries
implants the Jarvik-7 artificial
heart into Dr. Barney Clark
(he survived 112 days)
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Why Heart Substitutes Fail
Immune response “rejects” transplant or
side effects due to immune suppression
 Infection due to tubes and wires passing
through skin
 Formation of clots
 Damage to red blood cells
 Lack of pulsatile blood flow?

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Design Process
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Identify the problem or need to address
Specify details/criteria of an adequate
solution to your problem
Implement various solutions that meet the
criteria you specified
Test to determine which solution is most
viable
Further testing to refine the solution you
chose
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Design Refinement

Process is iterative
Identify Problem
– You need to repeat
various steps after
testing
– Make design changes
based on test results

Specify Criteria
Implement Design
Failed designs
– Design didn’t meet
criteria
– Could be due to
inappropriate criteria
Test Design
Refine Design
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Criteria for a Heart
Substitute
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Must fit into chest cavity and connect to atria,
pulmonary artery and aorta quickly
Provide an adequate blood flow (8 – 10
liters/min)
Send deoxygenated blood to the lungs and
oxygenated blood to the body
Operate continuously for an indefinite period
of time
Provide adequate warning if something is
wrong or if it is going to fail
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Criteria for a Heart
Substitute
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Should increase/decrease blood flow based
on patient activity level
Should not evoke an immune response
No wires or tubes that penetrate the skin
Should not produce blood clots
Should not damage red blood cells
Ideally should have pulsatile blood flow
Many others we haven’t thought of!
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The AbioCor® Heart
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Implanted into 59 year
old Robert Tools on July
2, 2001 at Jewish
Hospital in Louisville KY
(96 days)
Patient is able to walk
around, organs are
functioning normally,
undergoing daily
rehabilitation for
eventual release
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How the AbioCor® Heart
Works

Hydraulic pump forces
blood to lungs and body
 Power is provided by an
internal rechargeable
battery
 Battery is recharged by
coils on surface and
below skin
 Internal controller
monitors system and
controls pump speed
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Surgical Procedure

Implant controller,
battery and coil
 Connect patient to
heart-lung machine
 Cut away ventricles
 Sew grafts onto atria
and arteries
 Connect implants to
grafts
 Remove patient from
heart-lung machine
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AbioCor® Design Criteria
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Grapefruit size, weighs 2 lbs, requires a 7
hour surgery for implantation
Can provide up to 8 liters/min of blood to the
lungs and body
Has two chambers for pumping
deoxygenated blood to the lungs and
oxygenated blood to the body
Wireless energy transfer system allows for
continuous operation
Internal controller monitors operation
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AbioCor® Design Criteria
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Internal controller increases/decreases blood
flow based on blood oxygen levels
Materials are inert to the immune system
Completely contained within the chest – no
wires or tubing through skin!
Made of special materials and special pump
design to prevent clots and RBC damage
Pumping alternates between chambers,
creating a pulsatile blood flow
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